GPL-3.0 WITH LGPL-3.0 (this feels a bit odd, but it would be accurate technically speaking…) [or] LGPL-3.0
I strongly believe “LGPL-3.0” is the correct answer. "LGPL-3.0" is much simpler, it's much clearer to non-lawyers, and referring to it as its own name matches historical practice.
In *practice* the LGPL is practically always referred to as its own license, not as a tweak to another license. Historically the LGPL was implemented as a separate license, and the “tweak” is not a small one either (exceptions are usually small). All other license list systems (such as Debian and Fedora's) treat it as a separate license, so there is strong historical precedence to treating it as its own license (if no other reason than backwards compatibility).
